蔬菜、水果中多农药残留的筛查

近年来,食品安全问题引起了人们的高度重视,农药残留污染是制约食品安全的重要因素.在食品农药残留检测方法中,农药残留检测的种类越来越多,农药残留的限量标淮越来越严,人们对食品中农药残留的检测正在不断地探索快速准确的有效方法[1].解卷积报告软件(DRS)是由安捷伦公司研发,其目的主要用于农药和可疑内分泌干扰物的筛查.该软件由安捷伦质谱工作站、自动质谱解卷积和鉴定系统(AMDIS)以及NIST检索三部分组成.AMDIS需要使用包含有保留时间的自动质谱解卷积和鉴定系统.DRS能大大提高复杂基质中痕量化合物的定性能力,并且在SCAN和SIM两种模式下均可采用DRS进行数据处理.保留时间锁定(RTL)和RTL数据库是DRS的一个组成部分,它无需使用标样,只需采用数据库中建立的GC/MS条件,即可实现对农药和一些内分泌干扰物分析鉴定.     

GC-Q/TOF MS技术快速鉴定防风挥发油中的成分

采用气相色谱－四极杆飞行时间串联质谱（GC－Q/TOF MS）技术对中药防风挥发油中的化学成分进行鉴定。首先在标准EI电离源模式下采集样品,通过定性软件对数据进行解卷积和NIST库比对,鉴定出库内化合物82种,包括烃类、醛酮类、醇类、酸类和酯类。此外,采用GC－Q/TOF MS的低能量电离源（Lower energy）模式,确定未知化合物的分子离子峰;采集二级质谱,获得碎片离子信息,推断分子式,并结合Chemspider数据库,鉴定了未知物结构。运用该方法鉴定出NIST库外化合物2种,分别为（5E,7E,11S）-5,11-二甲基-5,7-十四碳二烯-1-炔-4-醇和（6S,7E,9E）-7,9-十七碳二烯-11,13-炔-6-醇。同时鉴定了库内化合物3种,为2,4-癸二烯醛、肉豆蔻酸和棕榈酸甲酯,与自动匹配结果相一致,验证了该方法的可行性。综上,从防风挥发油中共鉴定出84种化学成分。该研究丰富了GC－Q/TOF MS在中药防风挥发油中的运用,也为其他物质的快速全面鉴定提供了新思路,尤其是GC－Q/TOF MS的Lower energy 和MS/MS联用模式适用于NIST库中未收录化合物的准确快速鉴定。     

顶空/气相色谱-质谱联用结合化学计量学分析金属油墨印刷纸制品中气味物质

利用顶空/气相色谱－质谱联用法结合化学计量学分析3种原纸板及3种金属油墨印刷纸板中的挥发性物质及其差异。将样品剪裁后经顶空/气相色谱－质谱（HS/GC - MS）检测,结合MS－DIAL软件解卷积、NIST质谱库和物质保留指数定性分析,采用峰面积归一法计算各物质的相对含量,并计算相对气味活性值（ROAV）,分析金属油墨印刷纸板中关键气味贡献物质及其影响。结果表明,所有纸样中共检出63种化合物,其中鉴定出46种挥发性物质,包括醛类、酮类、烷烃类和烯烃类等化合物。金属油墨印刷后使得纸板产生更多醛酮类挥发性化合物,影响纸板整体的气味特征。筛选出苯甲醛、正辛醛、（E, E）-2,4-庚二烯醛、正癸醇、2-戊基呋喃等19种关键气味物质,建立主成分分析（PCA）、正交偏最小二乘判别分析（OPLS－DA）及层次聚类分析（HCA）模型,区分效果不明显,结果说明这些物质在不同原纸板及其金属油墨印刷纸板中均有分布。     

60Co-γ辐照对食品接触用复合包装袋中挥发性化合物的影响

针对辐照杀菌会使塑料包装产生未知辐解产物的问题,该文采用顶空气相色谱－质谱法（HS/GC－MS）结合MS－DIAL软件对60Co-γ辐照（0 ~ 10 kGy）后的19种商用塑料复合包装袋中的挥发性有机物（VOCs）进行检测。以MS－DIAL软件对谱图的解卷积、峰对齐及物质定性结果,以正交偏最小二乘法判别分析（OPLS－DA）模型对辐照前后材料的VOCs组成进行分析,考察不同辐照剂量下复合包装材料中VOCs组成的变化。结果显示,复合包装中的VOCs以聚合物降解产物烷烃和烯烃为主,60Co-γ辐照前后复合包装中的VOCs组成具有显著差异,且包装产生的VOCs总量随辐照剂量的增加而递增。通过OPLS－DA模型投影变量重要度（VIP）值筛选出17种对差异贡献较大的物质,这些差异物质大多为材料的降解产物,总体呈现检出量随辐照剂量增加而递增的趋势。该研究结果为辐照包装中挥发性非有意添加物质数据库的建立提供了依据。     

超临界流体色谱-气相色谱质谱法测定主流烟气中酯类化合物

构建了一种超临界色谱(SFC)-GC-MS方法,并用来检测卷烟主流烟气粒相物中酯类物质。用超临界流体对捕集卷烟主流烟气粒相物的剑桥滤片进行萃取,将萃取得到的香气成分用SFC进行初步分离,划分成3段,将分离出的3段馏分,分别用GC/M S进行检测分析。检测数据显示,样品不分段直接进样用GC/MS分析,总共检测出了11种酯类化合物;然而,经SFC分段后,再用GC/MS分析,总共检测出了31种酯类化合物。经SFC分离后的各段化合物峰形较好,基本不重叠,为主流烟气中酯类成分检测提供一种新方法。     

超高效液相色谱-四极杆-飞行时间质谱定性研究茶叶籽中的酚类化合物

采用超高效液相色谱(UHPLC)-四极杆-飞行时间质谱(Q-TOF/MS)技术定性分析茶叶籽中的酚类化合物。茶叶籽样品经乙醇水溶液提取后经反相色谱分离,通过Q-TOF/MS进行化合物的鉴定。基于山茶属及相关植物化学组成的文献,建立了一个含有106种酚类化合物的数据库。对UHPLC-Q-TOF/MS采集得到的一级质谱数据进行数据库检索,然后对检索到的化合物色谱峰进行二级质谱扫描,根据得到的碎片离子推断化合物的结构。初步推断出茶叶籽提取物中的24种酚类化合物,包括13种酚酸类、4种儿茶素类和7种黄酮类化合物,并通过与标准品比对,进一步确证了这些化合物。结果表明UHPLC-Q-TOF/MS技术可以用于对茶叶籽中酚类化合物进行快速、准确、可靠的定性分析,促进新化合物的发现与鉴别。     

吹扫/捕集-热脱附气质联用法对荷叶挥发油成分的对比分析

采用同时蒸馏萃取提取得到荷叶挥发油, 通过吹扫/捕集-热脱附法(P&T-TD)对上述提取物中挥发性成分进行富集, 以气质联用(GC/MS)进行定性检测, 同时与直接进样GC/MS法分析的成分进行比较. 两种方法成功分离分析出有机酸、酯、醛、醇、酚、烷烃、芳香烃、烯烃以及含氮、硫、氧杂原子的化合物等共计84种成分, 其中P&T-TD GC/MS鉴定出63种有机化合物, GC/MS鉴定出41种有机化合物, 有20种成分共同检出. 对比分析表明: P&T-TD GC/MS的吹扫/捕集-热脱附过程能富集各种组分, 相比GC/MS分析, 可以鉴定出微量成分及更多挥发性和半挥发性成分, 在精油等挥发性成分的分析检测中使用优势明显.     

大叶桉叶挥发油的化学成分研究

用挥发油提取器提取大叶桉干叶中的挥发油,利用色质联用(GC/MS)产生的双线性数据,藉化学计量学分辨方法,得到了各组分的纯物质色谱峰和质谱图。根据色谱保留时间,同时利用解析所得的纯物质质谱图在NIST质谱数据库进行相似检索来对各个组分进行定性分析;采用色谱峰面积归一法计算各化合物的相对含量。共分离了113个化合物,鉴定了其中90个,占总挥发油的93.28%。主要为萜类、萜醇类等化合物,还成功地检测出一些色谱分离不完全和低含量的组分。     

气相色谱-质谱联用法分析全氟酰氟

采用气相色谱-质谱联用技术(GC/MS)对电化学氟化法生产的全氟环己烷酰氟产品中主要产物全氟酰氟进行了检测。在60℃下,采用甲醇对全氟环己烷酰氟产品进行甲酯化处理。考察了不同长度,极性及膜厚的毛细管色谱柱的分离效果。以KB-1MS毛细管色谱柱(90 m×0.25 mm×1.0μm)为分离柱,采用GC/MS法对全氟酰氟组成进行了定性与定量分析;结合有机质谱学裂解规律,分别对环状全氟羧酸甲酯、饱和直链全氟羧酸甲酯和单不饱和脂肪酸甲酯的裂解方式和质谱特征进行了分析归纳。通过质谱数据库检索、标准品对照及已知全氟化合物的质谱信息分析,共鉴定出5种全氟酰氟,其中包括两种异构体;测得全氟环己烷酰氟约占总全氟酰氟含量的65%。     

GC-MS/MS法检测并确证纺织品中5种有机锡化合物

建立了气相色谱-串联质谱法(GC-MS/MS)检测和确证纺织品中5种有机锡(一丁基锡、二丁基锡、三丁基锡、二辛基锡、三苯基锡)的快速有效方法。样品经提取、衍生和正己烷液液萃取后,以GC-MS/MS选择反应监测模式(SRM)进行定性定量测定。结果表明,方法在0.02～0.50 mg/L范围内线性关系良好(r>0.999);5种有机锡化合物的定量下限(S/N≥10)为0.03～0.05 mg/kg;加标水平为0.05～0.5 mg/kg时,5种不同材质阴性样品(棉布、真丝、涤纶、羊毛布、棉/尼混纺)的平均回收率为82%～110%,相对标准偏差(RSD,n=5)为2.1%～7.5%。所建立的方法具有选择性强、灵敏度高、定性定量准确等优点,可以弥补气相色谱法(GC)和气相色谱-质谱法(GC-MS)在确证方面的不足,也弥补了液相色谱-串联质谱法(LC-MS/MS)只能检测三取代基有机锡化合物的局限性。     

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection applied to the determination of pesticides in food extracts

The separation provided by conventional gas chromatography (1D-GC) can be significantly enhanced by using comprehensive two-dimensional GC (GC X GC) instead. Combination with mass spectrometric detection is desirable for unambiguous confirmation of target compounds and the provisional identification of unknowns. A GC X GC system using a cryogenic modulator was coupled to a time-of-flight mass spectrometric (TOF MS) detector. With the determination of pesticides in vegetable extracts as an example, it was demonstrated that GC X GC improves the separation dramatically. All 58 pesticides of interest could be identified using their full-scan mass spectra, which was not possible when using ID-GC-TOF MS. In addition, the high scan speed of the TOF MS allowed the deconvolution of compounds partly co-eluting in GC X GC.     

Analysis of gin essential oil mixtures by multidimensional and one-dimensional gas chromatography/mass spectrometry with spectral deconvolution

The composition of essential oils and their mixtures used to formulate gin is usually too complex to separate all sample components by standard capillary gas chromatography (GC). In particular, minor constituents that possess important organoleptic properties can be masked by co-elution with major sample components. A solution is provided that combines gas chromatography/mass spectrometry (GC/MS) with "interactive" spectral deconvolution software. Sequential two-dimensional (2D) GC/MS is used to produce a target compound library, with orthogonal GC-GC providing the separation power required to obtain peak retention times and the corresponding mass spectra needed for the deconvolution database. The combination of these two techniques, mass spectral deconvolution and automated sequential 2D-GC/MS, offers a very effective synergy for both identifying key constituents that determine the perception of flavor and aroma and the quality control needed to analyze mixtures of complex essential oils.     

Sequential stir bar extraction,thermal desorption and retention time locked GC–MS for determination of pesticides in water

A method based on sequential stir bar sorptive extraction followed by automated thermal desorption–GC–MS for the determination of pesticides in underground and superficial water samples has been developed. Retention time locked GC–MS and deconvolution Automated Mass Spectral Deconvolution and Identification System software allows the use of pesticide databases for identification and quantification in routine applications. Quantitation limits and repetitivity using full scan mass spectrometric determination guarantee the applicability of the method, which enables considerable savings to be made in total analysis time, with data processing times of around 2 min/sample.     

Deconvolution gas chromatography/mass spectrometry of urinary organic acids--potential for pattern recognition and automated identification of metabolic disorders

The National Institute of Standards and Technology (NIST) Automated Mass Spectral Deconvolution and Identification System (AMDIS) is applied to a selection of data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of urinary organic acids. Mass spectra obtained after deconvolution are compared with a special user library containing both the mass spectra and retention indices of ethoxime-trimethylsilyl (EO-TMS) derivatives of a set of organic acids. Efficient identification of components is achieved and the potential of the procedure for automated diagnosis of inborn errors of metabolism and for related research is demonstrated.     

Identification of volatiles from pineapple (Ananas comosus L.) pulp by comprehensive two-dimensional gas chromatography and gas chromatography/mass spectrometry

Combining qualitative data from the chromatographic structure of 2-D gas chromatography with flame ionization detection (GC×GC-FID) and that from gas chromatography-mass spectrometry (GC/MS) should result in a more accurate assignment of the peak identities than the simple analysis by GC/MS, where coelution of analytes is unavoidable in highly complex samples (rendering spectra unsuitable for qualitative purposes) or for compounds in very low concentrations. Using data from GC×GC-FID combined with GC/MS can reveal coelutions that were not detected by mass spectra deconvolution software. In addition, some compounds can be identified according to the structure of the GC×GC-FID chromatogram. In this article, the volatile fractions of fresh and dehydrated pineapple pulp were evaluated. The extraction of the volatiles was performed by dynamic headspace extraction coupled to solid-phase microextraction (DHS-SPME), a technique appropriate for slurries or solid matrices. Extracted analytes were then analyzed by GC×GC-FID and GC/MS. The results obtained using both techniques were combined to improve compound identifications.     

Comprehensive chemical profiling of Guizhi Fuling capsule by the combined use of gas chromatography-mass spectrometry with a deconvolution software and rapid-resolution liquid chromatography quadrupole time-of-flight tandem mass spectrometry

Herbal formulations are complex natural mixtures. Researchers usually tend to focus more on analysis of nonvolatile components but pay less attention to volatile compounds. In this study, an analytical strategy combining two approaches was established for comprehensive analysis of herbal formulations. Guizhi Fuling capsule (GFC), a drug approved by the FDA to enter phase II clinical trial for treatment of primary dysmenorrhea, was taken as a case for analysis. Gas chromatography–mass spectrometry (GC‐MS) with automated mass spectral deconvolution and identification system (AMDIS) led to rapid identification of 48 volatile components including four acetophenones, three fatty acid esters, 13 phenylpropanoids and 19 sesquiterpenes. Most of them were found from Guizhi. The volatile oils of Guizhi have been proved to exhibit many pharmacological activities. This is helpful in understanding the pharmacological mechanism of GFC. Furthermore, AMDIS turned out to be efficient and reliable for analysis of complex herbal formulations. Rapid‐resolution liquid chromatography (RRLC) coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF MS/MS) allowed the identification of 70 nonvolatile components including six acetophenones, 12 galloyl glucoses, 31 monoterpene glycosides, three phenols and 12 triterpene acids. Fragmentation behaviors of assigned components, especially triterpene acids, which are hard to identify by low‐resolution MS, were first investigated by TOF MS/MS. Characteristic ions and typical loss of assigned triterpene acids were summarized. Combinatorial use of GC‐MS‐AMDIS and RRLC‐ESI‐Q‐TOF MS/MS could be of great help in global qualitative analysis of GFC, as well as other herbal products. Copyright © 2012 John Wiley & Sons, Ltd.     

Tracking juniper berry content in oils and distillates by spectral deconvolution of gas chromatography/mass spectrometry data

The complex nature of botanicals and essential oils makes it difficult to identify all of the constituents by gas chromatography/mass spectrometry (GC/MS) alone. In this paper, automated sequential, multidimensional gas chromatography/mass spectrometry (GC-GC/MS) was used to obtain a matrix-specific, retention time/mass spectrometry library of 190 juniper berry oil compounds. GC/MS analysis on stationary phases with different polarities confirmed the identities of each compound when spectral deconvolution software was used to analyze the oil. Also analyzed were distillates of juniper berry and its oil as well as gin from four different manufacturers. Findings showed the chemical content of juniper berry can be traced from starting material to final product and can be used to authenticate and differentiate brands.     

气相色谱／质谱法鉴定甲基异丁基酮产品中的杂质组分

采用ＧＣ／ＭＳ联用技术分离出甲基异丁基酮产品中６个杂质峰。将标准图谱库，质量色谱图等手段结合起来鉴定出７种杂质，并用标样，双柱对部分ＧＣ／ＭＳ的结果进行了证实，为产品质量控制提供依据。     

Study of automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis

The effects of overlapping levels and concentration ratios of overlapping components, and of scan rates of the mass spectrometer, on the capability of the automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis were studied. To investigate the capability of AMDIS in removing interferences from the overlapping peaks, this system was applied to data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of two overlapping (co-eluting) pesticides (beta-HCH and PCNB) in full scan mode. Differences in overlap levels, the concentration ratios of the two overlapping components and the scan rates of the instrument were studied. When the difference in scan number of overlapping compounds was equal to 1 scan, AMDIS incompletely extracted 'purified' mass spectra but as the difference increased to 3 or more scans, complete correct spectra could be extracted. The results also show that when the scan rate was in the range of 0.4-0.90 s/scan and the concentration ratios of the target compound/interference were above 1/5, there were ideal deconvolution results for this approach. To further study the application of AMDIS to pesticide residue analysis, AMDIS was applied to the identification of pesticides spiked in real samples (cabbage and rice). Typical pesticides being evaluated were identified using AMDIS at concentrations >50 ng/g in the extracts.